Fix newer Windows 10 awful performance with d3d9 software vertex processing

[mirh]

See Nucleoprotein/OneTweakNG#1 (comment)
https://docs.microsoft.com/en-us/windows/win32/direct3d9/d3dcreate
https://social.msdn.microsoft.com/Forums/en-US/a84dce94-49f4-4118-9e68-fe412c909ee4/directx-9-program-runs-terribly-after-win10-update-1607

Perhaps switching to mixed and hardware one may be already some solution (idk I'm not a dev), but if the original game devs didn't think to it my uneducated guess would be there was a legit reason.

[elishacloud]

Interesting. It looks like changing the vertex buffer to use system memory and switching the vertex processing to mixed mode solved the performance issues. Mixed mode processing is not normally recommended by Microsoft. But I suppose adding an option for this would be good.

[mirh]

I mean, to be fair, the last link could as well be just amd-specific.. they have been skimping on the d3d9 driver as of the last years in turn.
But nice for the option.

Assuming it actually ever was just for retrocompatibility, I wonder if it couldn't be safe to have all vertex processing be forced on hardware on say akk >DX10 or >SM3 gpus?

[mirh]

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9451/diffs
Not exactly linked to the problem here, but I guess you might found interesting these behind the scenes factlets.

[mirh]

Mhh, so, I just got some testing (yes, sorry for the lazy ass)
But ForceMixedVertexProcessing doesn't really help much, while ForceSystemMemVertexCache totally nukes framerate.

Maybe forcing hardware processing could do it?

[elishacloud]

Forcing hardware processing should do it. But may also cause graphical issues is the hardware cannot support somethings. Though it should be less of an issue with d3d9, I think. There is already an option to ForceMixedVertexProcessing. I could create a new option to ForceHardwareVertexProcessing.

[mirh]

Not really sure what could be the point of forcing modes if it isn't to improve performance (also was there any specific reason behind ForceSystemMemVertexCache?), but maybe you could have a single option with an integer value rather than a boolean.

EDIT: nevermind, over at dxwnd they report quite the success with the flags. It's just that they are just a drop in the bucket compared to all the other changes.